1. Field of the Invention
The present invention relates to a white light emitting device and a white light source module using the same, and more particularly, to a white light emitting device beneficially applicable to a backlight unit of a liquid crystal display to ensure high color reproducibility, and a white light source module using the same.
2. Description of the Related Art
Recently, a light emitting diode (LED) is highlighted as a light source of a backlight unit (BLU) employed in liquid crystal displays such as lap top computers, monitors, mobile phones and TVs. A cold cathode fluorescent lamp (CCFL) has been in use as a white light source of the BLU, but lately, a white light source module using the LED has captured attention due to its advantages such as better color representation, environment friendliness, higher performance and lower power consumption.
In a conventional white light source module for the BLU, a blue LED, a green LED and a red LED are arranged on a circuit board. FIG. 1 illustrates an example of such arrangement. Referring to FIG. 1, a white light source module 10 for a BLU includes a red R LED 12, a green G LED 14 and a blue LED 16 arranged on a circuit board 11 such as a printed circuit board. The R, G, and B LEDs 12, 14, and 16 may be mounted on the board 11 in a configuration of packages each including an LED chip of a corresponding color, or lamps. These R, G, and B LED packages or lamps may be repeatedly arranged on the board to form an overall white surface or line light source. As described above, the white light source module 10 employing the R, G, and B LEDs is relatively excellent in color reproducibility and an overall output light can be controlled by adjusting a light amount of the R, G, and B LEDs.
However, in the white light source module 10 described above, the R, G, and B LEDs 12, 14, and 16 are spaced apart from another, thereby potentially posing a problem to color uniformity. Moreover, to produce white light of a unit area, at least a set of R, G, and B LED chips is required since the three-colored LED chips constitute a white light emitting device. This entails complicated circuit configuration for driving and controlling the LED of each color, thus leading to higher costs for circuits. This also increases the manufacturing costs for packages and the number of the LEDs required.
Alternatively, to implement a white light source module, a white light emitting device having a blue LED and a yellow phosphor has been employed. The white light source module utilizing a combination of the blue LED and yellow phosphor is simple in circuit configuration and low in price. However, the white light source module is poor in color reproducibility due to relatively low light intensity at a long wavelength. Therefore, a higher-quality and lower-cost LCD requires a white light emitting device capable of assuring better color reproducibility, and a white light source module using the same.
Accordingly, there has been a call for maximum color reproducibility and stable color uniformity of the white light emitting device adopting the LED and phosphor, and the white light source module using the same.